Friday, September 26, 2014

Ed Witten still believes in string theory

At a 1990 conference on cosmology, I asked attendees, who included folks like Stephen Hawking, Michael Turner, James Peebles, Alan Guth and Andrei Linde, to nominate the smartest living physicist. Edward Witten got the most votes (with Steven Weinberg the runner-up). Some considered Witten to be in the same league as Einstein and Newton. Witten was and is famous for his work on string theory, which unifies quantum mechanics and relativity and holds that all of nature’s forces—including gravity–stem from infinitesimal particles wriggling in a hyperspace consisting of many extra dimensions.

Even then, string theory — which some enthusiasts (not including Witten) called a “theory of everything” – was extremely controversial, because there seemed to be no way to confirm experimentally the existence of strings or the extra dimensions they supposedly inhabit.

Witten has somehow convinced mathematicians and physicists that he is a great genius, even tho he does not do straight math or straight physics. Some of his math ideas have been turned into legitimate proofs by others. Not sure if any of his physics ideas have panned out.

Horgan: Do you see any other rivals for a unified theory of physics?

Witten: There are not any interesting competing suggestions. One reason, as remarked in “Unravelling,” is that interesting competing ideas (twistor theory, noncommutative geometry, …) tend to be absorbed as part of a larger picture in string theory. The competing interesting ideas have been very fragmentary and have tended to gain power when absorbed in string theory. ...

Witten: Personally, I hope the landscape interpretation of the universe would turn out to be wrong, as I would like to be able to eventually calculate from first principles the ratio of the masses of the electron and muon (among other things). However, the universe wasn’t made for our convenience. Plenty of leading physicists — prominent examples being Steve Weinberg and Martin Rees – have taken the acceleration of the cosmic expansion seriously as a hint that a landscape interpretation of the universe may be correct.

This is the opinion of a true believer. Whatever he sees, he finds a way to interpret it to match his beliefs from 30 years ago.

Horgan: Do you agree with Sean Carroll that falsifiability is overrated as a criterion for distinguishing science from pseudo-science?

Witten: Scientists aim to get as reliable and precise an understanding of nature as we can. The gold standard is a precise prediction that can be tested in a precise way in a laboratory experiment. Experiments that disprove theories are an important part of the scientific process.

With that said, it is a little too narrow to claim that science consists of trying to falsify theories because a lot of science consists of trying to discover things. (Chemists who attempt a new synthesis could say they are trying to falsify the hypothesis that this new synthesis won’t work. But that isn’t what they usually say. People who search for life on Mars could say they are trying to falsify the hypothesis that there is no life on Mars. Again, people don’t usually talk that way.)

Witten attacks a straw man, as nobody ever said that science consists only of trying to falsify theories. As Horgan said, it is a criterion for distinguishing pseudoscience. Karl Popper argued that Sigmund Freud would not accept anything as falsifying his theory of dream interpretation, and hence it is unscientific (and pseudoscience). Popper was right, and falsifiability is a useful criterion.

Carroll and Witten don't like it because they promote ideas that are no more testable than Freud's dream interpretations. Like the multiverse and string theory.

There is a high probability that supersymmetry, if it plays the role physicists suspect, will be confirmed in the next decade. The existing accelerators that have a chance of doing so are the proton collider at the Department of Energy’s Fermi Lab in Batavia, Ill., and the electron collider at the European Center for Nuclear Research (CERN) in Geneva.

Speaking of scientists being wrong, Tyson is apparently still refusing to admit that he has been making up quotes in speeches, and there is a Wikipedia edit war about it. This is pathetic. The Bush quote is almost directly opposite what Bush said. Others have been disgraced for inventing quotes. I try to verify quotes on this blog. Occasionally I'll use a quote that I cannot verify, but then I will say so.

1 comment:

I could care less if Witten is above or below average intelligence. In the arena of accomplishment a persons intelligence quotient is meaningless except as small talk over cocktails. When people claim someone is a 'genius', what they usually mean is that someone is a 'celebrity'.

Tyson is a true believer in his own celebrity. A pity he can't tell the difference between an actual fact and his own ego.